<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Cache
 * @subpackage Zend_Cache_Frontend
 * @copyright  Copyright (c) 2005-2011 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: Function.php 23775 2011-03-01 17:25:24Z ralph $
 */

/**
 * @see Zend_Cache_Core
 */
require_once 'Zend/Cache/Core.php';

/**
 * @package    Zend_Cache
 * @subpackage Zend_Cache_Frontend
 * @copyright  Copyright (c) 2005-2011 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Cache_Frontend_Function extends Zend_Cache_Core {
	/**
	 * This frontend specific options
	 *
	 * ====> (boolean) cache_by_default :
	 * - if true, function calls will be cached by default
	 *
	 * ====> (array) cached_functions :
	 * - an array of function names which will be cached (even if cache_by_default = false)
	 *
	 * ====> (array) non_cached_functions :
	 * - an array of function names which won't be cached (even if cache_by_default = true)
	 *
	 * @var array options
	 */
	protected $_specificOptions = array ('cache_by_default' => true, 'cached_functions' => array (), 'non_cached_functions' => array () );
	
	/**
	 * Constructor
	 *
	 * @param  array $options Associative array of options
	 * @return void
	 */
	public function __construct(array $options = array()) {
		while ( list ( $name, $value ) = each ( $options ) ) {
			$this->setOption ( $name, $value );
		}
		$this->setOption ( 'automatic_serialization', true );
	}
	
	/**
	 * Main method : call the specified function or get the result from cache
	 *
	 * @param  callback $callback         A valid callback
	 * @param  array    $parameters       Function parameters
	 * @param  array    $tags             Cache tags
	 * @param  int      $specificLifetime If != false, set a specific lifetime for this cache record (null => infinite lifetime)
	 * @param  int      $priority         integer between 0 (very low priority) and 10 (maximum priority) used by some particular backends
	 * @return mixed Result
	 */
	public function call($callback, array $parameters = array(), $tags = array(), $specificLifetime = false, $priority = 8) {
		if (! is_callable ( $callback, true, $name )) {
			Zend_Cache::throwException ( 'Invalid callback' );
		}
		
		$cacheBool1 = $this->_specificOptions ['cache_by_default'];
		$cacheBool2 = in_array ( $name, $this->_specificOptions ['cached_functions'] );
		$cacheBool3 = in_array ( $name, $this->_specificOptions ['non_cached_functions'] );
		$cache = (($cacheBool1 || $cacheBool2) && (! $cacheBool3));
		if (! $cache) {
			// Caching of this callback is disabled
			return call_user_func_array ( $callback, $parameters );
		}
		
		$id = $this->_makeId ( $callback, $parameters );
		if (($rs = $this->load ( $id )) && isset ( $rs [0], $rs [1] )) {
			// A cache is available
			$output = $rs [0];
			$return = $rs [1];
		} else {
			// A cache is not available (or not valid for this frontend)
			ob_start ();
			ob_implicit_flush ( false );
			$return = call_user_func_array ( $callback, $parameters );
			$output = ob_get_clean ();
			$data = array ($output, $return );
			$this->save ( $data, $id, $tags, $specificLifetime, $priority );
		}
		
		echo $output;
		return $return;
	}
	
	/**
	 * ZF-9970
	 *
	 * @deprecated
	 */
	private function _makeId($callback, array $args) {
		return $this->makeId ( $callback, $args );
	}
	
	/**
	 * Make a cache id from the function name and parameters
	 *
	 * @param  callback $callback A valid callback
	 * @param  array    $args     Function parameters
	 * @throws Zend_Cache_Exception
	 * @return string Cache id
	 */
	public function makeId($callback, array $args = array()) {
		if (! is_callable ( $callback, true, $name )) {
			Zend_Cache::throwException ( 'Invalid callback' );
		}
		
		// functions, methods and classnames are case-insensitive
		$name = strtolower ( $name );
		
		// generate a unique id for object callbacks
		if (is_object ( $callback )) { // Closures & __invoke
			$object = $callback;
		} elseif (isset ( $callback [0] )) { // array($object, 'method')
			$object = $callback [0];
		}
		if (isset ( $object )) {
			try {
				$tmp = @serialize ( $callback );
			} catch ( Exception $e ) {
				Zend_Cache::throwException ( $e->getMessage () );
			}
			if (! $tmp) {
				$lastErr = error_get_last ();
				Zend_Cache::throwException ( "Can't serialize callback object to generate id: {$lastErr['message']}" );
			}
			$name .= '__' . $tmp;
		}
		
		// generate a unique id for arguments
		$argsStr = '';
		if ($args) {
			try {
				$argsStr = @serialize ( array_values ( $args ) );
			} catch ( Exception $e ) {
				Zend_Cache::throwException ( $e->getMessage () );
			}
			if (! $argsStr) {
				$lastErr = error_get_last ();
				throw Zend_Cache::throwException ( "Can't serialize arguments to generate id: {$lastErr['message']}" );
			}
		}
		
		return md5 ( $name . $argsStr );
	}

}
